1. Field of the Invention
This invention relates to motor driven doors and, more particularly, to a universal adapter unit for conventional garage doors such as those that are guided by guide rails disposed at the sides thereof.
2. Description of the Prior Art
A general mechanism is basically used to actuate garage doors of the type that are vertical when closed and when opened are stored in an overhead, horizontal position. Such sliding garage doors are generally mounted on two guide rails, one on each side thereof, the door having guide rollers at each side to rotate inside the guide rails. The guide rails are elongated reversed L-shaped members that are partly rounded at their corner and that are mounted to the sides of the frame of the garage defining the opening thereof and to its ceiling. The guide rails define channels which face inwards to receive the rollers of the door for movement therein.
The general actuating mechanism for the above garage doors is characterized by having a motor mounted to the ceiling of the garage centrally and rearward of the door opening. The motor drives a sprocket engaging a chain which is generally connected to the inner surface of the top panel of the door so as to pull the door from a closed to an open position thereof, and vice versa.
The drive mechanism disclosed in U.S. Pat. No. 1,916,651 issued on July 4, 1933 to Beeman et al., shows such a system but for a motor which is mounted to one side of the garage ceiling. To open the door, the motor drives a pair of chains connected to the lower side inner ends of the door. The door is closed when the same chains act in an opposite direction and pull on members that have one end thereof slidably engaged in the guide rails and another end connected to the upper inner part of the door. This door drive mechanism thus results in a complex and space consuming arrangement of sprockets, chains, connection members and springs. Furthermore, to drive the door, a shaft is required to extend across the garage, thereby occupying some of the headroom thereof.
Some doors, such as the one disclosed in U.S. Pat. No. 1,936,300, issued on Nov. 21, 1933 to Guss, are mounted in series on both sides thereof with chains to produce a pair of motor driven endless loops. Again, the motor is mounted to the ceiling of the garage at least a door's height rearward of the door opening thereof to horizontally accommodate the door in its open position. This reduces the available headroom in the garage.
U.S. Pat. No. 3,280,888, issued on Oct. 25, 1966 to Davis, discloses a motorized folding overhead door driven by an endless chain connected thereto and guided by upstanding guide means provided on the inner sides of the door frame. This mechanism driving a folding-type door therefore does not necessitate rearward extending guide rails as all the components therefor, including the motor, are conveniently located near the door frame although they occupy substantial body space thereat.
U.S. Pat. No. 3,834,080, issued on Sept. 10, 1974 to Lystad, disclosed a window regulator for a station wagon tailgate window wherein a manually operated handle drives a pair of sprockets each engaging at the top thereof apertures provided on a pair of drive tapes which extend downward on each side of the sprockets. The drive tapes have an end thereof connected to a lower edge of the window so as to drive the window up or down within a window guide. Both sides of the tapes loosely overhang the sprockets within elongated guide sleeves without being guided therein.
U.S. Pat. No. 4,656,780, issued on Apr. 14, 1987 to Miyauchi et al., is similar to the Lystad Patent as a sprocket is in driving engagement with a drive ball assembly guided in an elongated ball guide so as to impart bidirectional linear movement to a window panel mounted to one end of the drive ball assembly. The other end of the drive ball assembly is spring loaded to the distal end of the ball guide with respect to the window panel in order to bias the drive ball assembly in a direction to urge the window panel toward its closed position.
U.S. Pat. No. 4,685,248, issued on Aug. 11, 1987 to Hammond, discloses a pinion driven rack that is slidably engaged in a track defining a generally rectangular channel. The rack is further connected to a window to impart movement thereto.
None of the above drive mechanisms provide for a unit universally adaptable to doors of the type that slide from a vertical position towards a horizontal position along guide rails disposed on each side thereof.
The above drive mechanisms intended for garage doors are somewhat cumbersome as they take up headroom generally in the central portion of the garage. Furthermore, these drive mechanisms are generally of rather complex construction.